So I was reading this scientific article and stumbled upon the following phrase:
"winL is a subset of partL also containing objects within epsilon of r."
It's refering to distances as shown in the picture below (the gray part is winL, which contains the objects positioned within epsilon meters of r).
What exactly does it mean? I'm not a native English speaker and I don't know how to explain this.
Later edit: So I figured out a better, less technical example, inspired from the first answer. What does within mean when you say: "x is within an arbitrarily small distance of r".